Positive-contact mercury switch



Dec. 14, 1965 J. L. GRUPEN PosITIvE-coNTACT MERCURY SWITCH Filed Jan. 18, 1963 J4 2 2435 33 19 25 Zz J3 54 INVENTOR. JAMES L. GRUPE/V Bfm/ ATTORNEY United States Patent() 3,223,811 POSTHVE-CNTAC'I MERCURY SWITCH `lames L. Grupen, 1269 Lynn Way, Sunnyvale, Calif. Filed Jan. 18, 1963, Ser. No. 252,401 4 Claims. (Cl. 200-152) This invention relates to a positive-contact switch using a conductive liquid, such as mercury, for closing the electric circuit therethrough.

An object of the present invention is to provide a switch as characterized in which arcing is eliminated.

Another object of the invention is to provide a switch that, at circuit breaking or separation, has an increase in resistance prior to complete separation, and at contact or circuit closing, has a decrease in resistance until full contact is effected. As a result of the foregoing, the make and break of the switch generate minimum radio frequency interference.

A further object of the inveniton is to provide a positive-contact switch that generates a square-wave pattern, and eliminates tailing of current.

Other objects are to provide a switch in which electrical Contact is complete, has minimum resistance at points of contact until full contact is effected, is not subject to the adverse effects of vibration and mechanical shock, is totally enclosed so as to be safe for use in an explosive atmosphere, has reduced effects of contact oxidation, has a contact area that is variable and which reaches full capacity when the conductive liquid-mercuryis in full contact with movable conductors of the switch, and is adjustable to effect accurate timing repetitions of make and break.

This invention also has for its objects to provide such means that are positive in operation, convenient in use, easily installed in a working position and easily disconnected therefrom, economical of manufacture, relatively simple, and of general superiority and serviceability.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description and which is based on the accompanying drawing. However, said drawing merely shows, and the following description merely describes, preferred embodiments of the present invention, which are given by way of illustration or example only.

In the drawing, like reference characters designate similar parts in the several views.

FIG. 1 is an elevational view, lin quarter section, of one form of positive-contact switch according to the present invention and shown in the on or closed position thereof.

FIG. 2 is a similar View showing said switch oif or open.

FIG. 3 is an elevational view, in quarter section, of another form of positive-contact switch and shown in the on or closed position thereof.

The electric positive-contact switch that is illustrated in FIG. l comprises, generally, a conductive housing 5 that constitutes one terminal of the switch, an elongated member 6 axially movable in said body and formed to have a conductive portion 7 and a dielectric portion 8, a body of electrically conducting liquid 9, confined in the body 5, and means 1) to place said liquid under a constant pressure.

In the form of FIG. 3, the switch comprises a body 11 that is formed of end to end conductive portions 12 and 13 connected by a middle dielectric portion 14, an elon- 1 gated member 15 axially movable in the body 11 and formed to have a conductive end 16 and a dielectric end 17, two separate bodies 18 and 19 of electrically conductive liquid disposed and confined within the respective body portions 12 and 13, and separate means 20 and 21 to place said respective liquid bodies under constant pressure.

The housing 5 of the form of FIGS. 1 and 2 is advantageously made of steel or other suitable conductive material. Said body has an axial passage 22 that is closed by end caps 23 and 24 of dielectric material, such as Teon-a tetrafluorethylene polymer-or the equivalent plastic. Said caps have aligned bearing holes in which the member 6 is guided for axial movement. An intermediate portion of the body is thickened at 25 to provide end abutments 26 and 27.

The elongated member 6 is shown as a brass r-od 28 with a reduced end 29 and a reduced opposite end 30, the part between said ends constituting the mentioned conductive portion 7, the same having a free sliding fit in the bearing cap 23. A snap ring 31 on the end of portion 7 that is adjacent to the rod end 29 has slide-limiting engagement with the cap 23.

Said member 6 on the end 30 thereof is provided with the dielectric portion 8, in the case, in the form of a sleeve of Delrin or other tough, high impact plastic material. Said sleeve and the portion 7 of the member 6 are preferably the same diametral size, as shown. A dielectric flange or washer 32 is provided on the dielectric end of the member 6 and may be used for shifting said member.

It will be understood that, as required, the different dielectric or non-conductive parts above described may be made of acrylic resin, polymide resin, acetal resin, tetratluorethylene polymer plastic, or other comparable synthetic resins or plastics.

The body of conductive fluid 9mercury or a suitable ionized Huid-is confined in the b-ody 5 by the means 10. The latter is here shown as two natural or synthetic rubber sealing rings 33 and 34, the former between the shoulder formed by the end abutment 26 and the end cap 23, and the latter between the shoulder formed by the end abutment 27 and the end cap 24. An expansion spring 35 is interposed between the ring 34 and cap 24, the same imposing a bias on said ring 34 and, therefore, on the body of conductive liquid 9 between said two rings 33 and 34. As a consequence, the body of liquid 9 is forced into intimate contact with the inner surface of the body part 25 and that portion of the member 6 that is opposite thereto. It will be clear that, when the member 6 is shifted to the position of FIG. 1, there is an electric connection between body 5 and end 29 of member 6 and that, when the member 6 is shifted to the position of FIG. 2 wherein the body of liquid is in contact with the dielectric portion 8 of the member 6, no current can ow between body 5 and member 6.

Since the rings 33 and 34 are of the type that seal effectively against by-passing ilow of said liquid 9, this conductive liquid retains its position between said rings and is statistically disposed in the body 5 during make and break movements of the member 6.

In the switch illustrated in FIG. 3, each conductive body end 12 and 13 is provided with a terminal, respectively 36 and 37. The elongated member 15 is slidable, as before, but, in this case, the conductive end 16 of member 15 acts to bridge the two bodies of conductive liquid 18 and 19, thereby establishing an electric circuit that ows between the terminals 36 and 37.

It will be seen that each of the separate pressure-biasing means 20 and 21 is simi-lar to the described means 10 of the earlier-described form of the invention, and that when the member 15 is shifted to the left to bring the dielectric portion 17 thereof into contact with the liquid 19, the circuit is broken or opened even though the portion 16 of member 15 is still 4in Contact with the liquid 18.

As shown, an insulating sleeve 38 may be placed or provided as a coating around the body 11.

While the foregoing has illustrated and described what is now contemplated to be the best mode of carrying out the invention, the constructions are, of course, subject to modification without departing from the spirit and scope ofthe invention. Therefore, it is not desired to restrict the invention to the particular forms of construction illustrated and described, but to cover all modifications that may fall within the scope of the appended claims.

Having thus described this invention, what is claimed and desired to be secured by Letters Patent is:

1. A positive-contact electric switch comprising (a) an electrically conductive housing having an axial passage therethrough including a restricted area defined by a thickened wall portion terminating in spaced annular inwardly projecting abutments,

(b) opposed longitudinally spaced sealing rings in said passage arranged at each side of said restricted area and outwardly of said abutments, said rings projecting inwardly of said abutments and one' of said sealing rings being slidable in said passage,

(c) a body of electrically conductive liquid in said conductive housing between said rings,

(d) an elongated member adapted to be adjustably lslidably in said passage and through said spaced sealing rings and having a conductive end and a dielectric end,

(e) end caps of dielectric material xed at each end of said housing formed with axially aligned openings for the passage of said elongated member therethrough, and

(f) spring means in said housing engaging said slidable sealing ring and one of said end caps to impose constant axial pressure to said slidable sealing ring to cause the liquid to have contact pressure with both the conductive housing and either the conductive or dielectric end of the elongated member according to the adjusted position of the elongated member in the axial passage in said body.

2. A positive-contact switch according to claim 1 in which (a) the housing is divided into ends that are insulated from each other,

(b) the mentioned sealing rings, body of fluid, and biasimposing means being disposed within one of said housing ends, and

(c) second opposed sealing rings, body of fluid, and bias-imposing means being disposed in the other housing end.

3. A positive-contact switch according to claim 1 in which each of said two housing ends constitutes an electrical terminal, and a dielectric member is provided to electrically separate the same.

4. A positive-contact electric switch according to claim 2 in which the means to resiliently bias the rings toward each other comprises a pair of oppositely disposed coiled springs.

References Cited by the Examiner UNITED STATES PATENTS 2,901,580 8/1959 Kelly 20G-152 3,010,004 11/1961 Clarey 200-152 ROBERT K. SCHAEFER, Primary Examiner. BERNARD A. GILHEANY, Examiner. 

1. A POSITIVE-CONTACT ELECTRIC SWITCH COMPRISING (A) AN ELECTRICALLY CONDUCTIVE HOUSING HAVING AN AXIAL PASSAGE THERETHROUGH INCLUDING A RESTRICTED AREA DEFINED BY A THICKENED WALL PORTION TERMINATING IN SPACED ANNULAR INWARDLY PROJECTING ABUTMENTS, (B) OPPOSED LONGITUDINALLY SPACED SEALING RINGS IN SAID PASSAGE ARRANGED AT EACH SIDE OF SAID RESTRICTED AREA AND OUTWARDLY OF SAID ABUTMENTS, SAID RINGS PROJECTING INWARDLY OF SAID ABUTMENTS AND ONE OF SAID SEALING RINGS BEING SLIDABLE IN SAID PASSAGE, (C) A BODY OF ELECTRICALLY CONDUCTIVE LIQUID IN SAID CONDUCTIVE HOUSING BETWEEN SAID RINGS, (D) AN ELONGATED MEMBER ADAPTED TO BE ADJUSTABLY SLIDABLY IN SAID PASSAGE AND THROUGH SAID SPACED SEALING RINGS AND HAVING A CONDUCTIVE END AND A DIELECTRIC END, (E) END CAPS OF DIELECTRIC MATERIAL FIXED AT EACH END OF SAID HOUSING FORMED WITH AXIALLY ALIGNED OPENINGS FOR THE PASSAGE OF SAID ELONGATED MEMBER THERETHROUGH, AND (F) SPRING MEANS IN SAID HOUSING ENGAGING SAID SLIDABLE SEALING RING AND ONE OF SAID END CAPS TO IMPOSE CONSTANT AXIAL PRESSURE TO SAID SLIDABLE SEALING RING TO CAUSE THE LIQUID TO HAVE CONTACT PRESSURE WITH BOTH THE CONDUCTIVE HOUSING AND EITHER THE CONDUCTIVE OR DIELECTRIC END OF THE ELONGATED MEMBER ACCORDING TO THE ADJUSTED POSITION OF THE ELONGATED MEMBER IN THE AXIAL PASSAGE IN SAID BODY. 